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How to correctly install a Proximity Switch ?

Standard Target - Size

As per the CENELEC standard EN 50010, the rated operating distance of an Inductive Proximity Switch (IPS) is specified assuming that the target is a square plate, 1mm thick, made of mild steel. The dimensions of the square are indicated below.

Sensor Diameter Target Size (mm)
8mm flush or non-flush 8 x 8
12mm flush or non-flush 12 x 12
18mm Non-flush Mounting 18 x 18
18mm non-flush 24 x 24
30mm flush 30 x 30
30mm non-flush 45 x 45

Targets smaller than those specified above would result in sensing distances that are less than those specified.

Non-standard Target

Targets not of mild steel will result in sensing distances that are different from those specified. The approximate correction factors for various target materials are indicated below.


Target Material Correction Factor
(% of rated distance)
Cast Iron 110
Stainless Steel 70
Brass 50
Aluminium (thickness < 0.05mm) 90
Aluminium 40
Copper 40

As an example consider a switch with a rated operating distance of 10mm. This distance is specified for a Mild Steel target of dimensions as mentioned above. For a brass target of the same dimensions, however, the same switch would function at approx. 5mm.

Switch Mounting

Flush Mounting in Metal, as shown in the figure below, is possible only for those switches whose metal housing extends upto the sensing face. Furthermore, to avoid interference, adjacent switches should be mounted with separating distances, as indicated in the table below.




Non-flush Mounting, as shown in the figure below, is mandatory for those switches whose metal housing does not extend upto the sensing face. If mounted flush in metal, these switches will not function correctly. To prevent false actuation from the sides, therefore, these switches must be mounted in a metal-free zone as shown below. Furthermore, to avoid interference, adjacent switches should be mounted with separating distances, as indicated in the table below.





(mm) M8 M12 M18 M30
Flush Non-flush Flush Non-flush Flush Non-flush Flush Non-flush
D1 8 16 12 24 18 36 30 60
D2 4 8 8 16 20 32 40 60
D3 3 6 6 12 15 24 30 45
D4 - 24 - 36 - 54 - 90
H1 0 4 0 8 0 16 0 30

Installation of Switch cable

We recommend routing of the switch cable through a grounded, flexible metal conduit. No high voltage power cables should be routed through this conduit; cables of other switches can however, be accommodated within. Furthermore any high voltage power line should be routed a minimum of 100mm away from the switch cable, as shown in the figure below. The conduit or cable must be laid and secured in a manner that no forces are transmitted onto the switch. This is particularly important in applications where the cable is constantly moved. Note the location of the conduit clamp in the figure below.




Electrical Connections

These should be made as indicated below.

  

Care should be taken not to exceed the voltage limits specified - generally 10-30V for DC switches and 40-250V for AC switches. For DC switches, we recommend use of a regulated supply with ripple content less than 10%. Since AC switches, by themselves, are not protected against short circuits, we recommend an external series connection, with the load, of a 20 Ohm, 10Watt wirewound resistor and a 400mA fuse. This combination will provide adequate short circuit protection.
 
Dimensions

 
 
AVISORS suitable for flush mounting in metal do not have a projecting front cap. The l3 values, accordingly, apply only to AVISORS, suitable for Non-flush mounting in metal.
 
BODY NUTS
Thread Size d1
(Metric)
l2
min.
l3
max.
l3
max.
sw m d3
max.
M 8 x 1* 45 45 13 4 4 15
M 12 x 1* (Namur) 38 60 8 17 4 20
M 12 x 1 38 60 8 17 4 20
M 18 x 1* (Namur) 40 40 9 24 4 28
M 18 x 1 57 80 9 24 4 28
M 22 x 1.5 57 80 9 24 4 28
M 24 x 1.5 57 80 9 30 5 35
M 30 x 1.5* (Namur) 40 40 16 36 5 42
M 30 x 1.5 57 80 16 36 5 42
M 36 x 1.5 57 80 20 45 6 51